metamorphic

Weathered granitic gneiss

Quartz–feldspar–mica gneiss; compositionally related to granite

AI-generated identification · may be incorrect

Hardness about 6–7 Mohs; mottled gray, cream, tan, and brown with granular texture and faint foliation. Quartz and feldspar provide a glassy to dull luster; mica may create subtle sparkles, with poor cleavage overall.

Identified August 15, 2026More metamorphic →

Explore Weathered granitic gneiss in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed when granitic rock underwent high-grade metamorphism, recrystallizing and locally segregating its minerals; commonly Precambrian to Paleozoic in age. The rounded form and surface staining indicate prolonged weathering and transport.

Uses & applications

Used locally as landscaping stone, riprap, aggregate, and building material; attractive pieces may be collected as natural specimens, though this example has limited commercial value.

Geological facts

Gneiss commonly preserves evidence of deep crustal pressure and temperature, often displaying alternating light and dark mineral bands. Weathering can obscure the banding and make it resemble granite.

Field identification & locations

Look for interlocking quartz and feldspar grains, dark mica or amphibole, and any compositional banding; a glass-scratch test may confirm hardness, though field testing should be cautious. Common in ancient continental shields and metamorphic mountain belts.